docs: def verify_signature_block(certificate_file, content, signature):
      """
      Verifies the 'signature' over the 'content', trusting the
      'certificate'.
  
      :param certificate_file: the trusted certificate (PEM format)
      :type certificate_file: str
      :param content: The signature should match this content
      :type content: str
      :param signature: data (DER format) subject to check
      :type signature: str
      :return None if the signature validates.
      :exception SignatureBlockVerificationError
      """
  
      sig_bio = BIO.MemoryBuffer(signature)
      pkcs7 = SMIME.PKCS7(m2.pkcs7_read_bio_der(sig_bio._ptr()), 1)
      signers_cert_stack = pkcs7.get0_signers(X509.X509_Stack())
      trusted_cert_store = X509.X509_Store()
      trusted_cert_store.set_verify_cb(ignore_missing_email_protection_eku_cb)
      trusted_cert_store.load_info(certificate_file)
      smime = SMIME.SMIME()
      smime.set_x509_stack(signers_cert_stack)
      smime.set_x509_store(trusted_cert_store)
      data_bio = BIO.MemoryBuffer(content)
  
      try:
          smime.verify(pkcs7, data_bio)
      except SMIME.PKCS7_Error as message:
          raise SignatureBlockVerificationError(message)
      else:
          return None